MSU biologist’s work with crocodilians goes international

STARKVILLE — A Mississippi State University biologist’s fascination with crocodiles has brought together researchers from the United States and Australia to study the genetic building blocks of a reptile order.

In the process, they hope to discover ways to conserve endangered animals, harness the antibiotic properties of alligator blood and isolate the genes that determine gender.

“Humans have had a complex relationship with crocodilians for most of their history,” said David Ray, a researcher with the Mississippi Agricultural and Forestry Experiment Station and assistant professor in MSU’s Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology. “We respect and admire them, as evidenced by the numerous references to them in historical literature and art as well as the plethora of current television documentaries, but we’re also a bit terrified by them.

“They’re one of the few groups of animals out there that make a habit of considering people as potential food,” he said.

Ray said crocodilians include true crocodiles, alligators, caimans — which live in Central and South America — and gharials, an endangered species native to India.

“Crocodilians represent big business,” Ray said. “In the U.S., Australia and several other countries, alligator and crocodile skins and meat are valuable commodities.”

Ray recently received funding from the National Science Foundation for a collaborative project with other scientists involved in crocodilian research. Each researcher hopes the genetic information stored in the crocodilian genome will answer different questions. Ray is most interested in the role DNA plays in the body shape of all crocodilians.

Ray said a genome is the complete set of genes in an organism. A gene is a segment of DNA. He compared the information contained in a cell to the information found in a book.

“Imagine a cell is like a book. When you look inside the book, you see text made up of letters. Now, imagine the letters are all mixed up and only form a sentence every once in a while,” Ray said.

“When scientists look at the text and see a sentence that makes sense, that is a gene. That particular segment of DNA has letters in a unique order the scientists can identify. When we put all of those sentences together, we have text that makes sense — we have mapped out all of the genes of a genome,” he said.

Because genes determine physical and inheritable characteristics in an organism, scientists can figure out which genes determine which physical traits. For example, in the crocodilians, researchers hope to learn which genes determine how rough or smooth the saltwater crocodile’s skin is.

Out of the 2.5 billion “letters” in the crocodilian’s “text,” Ray and his colleagues hope to find 20,000 “sentences,” or genes, in the genomes of three crocodilians: the American alligator, the Australian saltwater crocodile and the Indian gharial.

Such significant genetic information could have an impact on wildlife conservation, including ways to preserve one of the research subjects, the gharial. This crocodilian is visibly different from its relatives, with completely webbed rear feet and a long, tapered snout that ends in a soft bulbous nose in males of the species.

Ray said there are only about 200 gharials left in the wild.

“Part of the reason for that is the difficulty these animals have surviving in environments other than the very specific one they are adapted to,” he said. “By gaining information from their genome, we increase our chances of improving captive and wild breeding programs.”

While genomic research is challenging and complex, Ray said this type of basic science is fundamental to understanding a wide range of topics that impact human health.

“Getting genome sequences of organisms gets us to the basics of what that organism is and where it came from,” he said. “The genome is the source of the variation we see in any population — it is where all of our differences and similarities come from,” he said. “Understanding the genomes can lead to improvements in medicine and to identifying the genetic causes and potential cures for diseases.”

Daniel Peterson, director of MSU’s Institute for Genomics, Biocomputing and Biotechnology, said the original scope of Ray’s NSF funding was limited to sequencing only a portion of the crocodile, alligator and gharial genomes.

“Recent breakthroughs in DNA sequencing technology, coupled with financial and technical support from the IGBB, permitted expansion of Dr. Ray’s research to include the complete genome sequencing of all three species,” Peterson said. “Crocodilians are the closest living relatives of birds. Information about crocodilian genomes will not only help protect crocodilians, but may provide insight into how to better protect birds in the wild and on the farm.”

Peterson said MSU formed the IGBB in 2010 to increase MSU’s role in the world of biomolecular research. Ray’s project is one of the IGBB’s largest research initiatives.

“MSU has the technology and expertise to make significant contributions to basic and applied science while advancing opportunities for students interested in biology and related careers,” he said.